Cutting the network from a GPRS Module

[Hicham M]

Hello,

I'm working on a project that involved a GPRS module (Telit HE 683), and i'm having trouble when the network is not available for long periods (1 to 4 hours) apparently the module freeze and doesn't response to any AT commands, the only solution is to cut totally the power supply.

I'm not sure 100% that the module freeze because of the absence of the network, so I want to simulate that in the lab.

My question is : if there is a simple way to simulate a cut of network ? my first idea is adding some basic RC filters to the antenna ? cause even when removing the antenna, the device still captures the network.

I would really appreciate if anybody can help me with this?

 

[vfone]

Replace the antenna with a 50 ohms dummy-load (using very short coax cable), or put the module in a shielded-box (preferable double-shielded metal walls).
Filters between antenna and module wouldn't help too much.

 

[Hicham M]

Replace the antenna with a 50 ohms dummy-load (using very short coax cable), or put the module in a shielded-box (preferable double-shielded metal walls).
Filters between antenna and module wouldn't help too much.

Thank you vfone for the tips, Would that work for GSM signal aswell ? and do you have any examples of shielded box ? maybe a place where i can buy them or a way to make it?

 

[Hicham M]

Is there someone who can give me more détails about where to find a shielded box to buy ??

 

[vfone]

**broken link removed**
https://www.rohde-schwarz.com/en/product/cmwz10-productstartpage_63493-10816.html

 

[FvM]

I presume the "cutting" problem is about insufficient shielding of the module antenna connection and possibly less than perfect ground connection. It won't happen with a module that has an onboard coaxial connector.

In this case, the suggested shielded box is probably the only promising way to isolate the module input from good GSM network at your place. If you try something on your own, you'll need good bypass capacitors and/or filters for module power supply and data lines, too.

I also expect that the antenna port of a telit GT683 terminal is sufficiently shielded for your purposes.

 

[Hicham M]

I presume the "cutting" problem is about insufficient shielding of the module antenna connection and possibly less than perfect ground connection. It won't happen with a module that has an onboard coaxial connector.

In this case, the suggested shielded box is probably the only promising way to isolate the module input from good GSM network at your place. If you try something on your own, you'll need good bypass capacitors and/or filters for module power supply and data lines, too.

I also expect that the antenna port of a telit GT683 terminal is sufficiently shielded for your purposes.

I'm not quiet sure if i understood everything you said, I have basic knowledge of telecommunication.

though, this problem happens only when the network service is not available for long period, i believe that this has nothing to do with the modem antenna cause we tested the network with cell phones aswell, and there are more than 200 units in the field and they all work just fine, just the units that are placed in certain areas where the network is hard to catch.

I tried to remove the antenna but the telit GT683 still can catch the network, and i think shielded box is not an option cause it cost a lot.

I'm going for the dummy load option,

Any recommendations for a good dummy load ?